Question

I have this piece of code in c#:

private static void _constructRow(SqlDataReader reader, system.IO.StreamWriter stwr, bool getColumnName)
{
  for (int i = 0; i < reader.FieldCount; i++)
   stwr.Writeline(String.Format("<td>{0}</td"), getColumnName ? reader.GetName(i) : reader.GetValue(i).ToString()));
}

I’m trying to understand what the part that start with “getColumnName ?” and ends with “.ToString()” does. I understood that it is a system.object type, but I have no idea what it specifically does or how it works.
I want that because of this: “reader” had multiple rows in it, and I want to writeline only specific rows.

If anyone can help me on either of those, I’d be grateful.

Answer 1

The function iterates over all columns in the data reader, then for each one:

If getColumnName returns true, it outputs the name of the column between the <td> tags, otherwise the value of the data.

To de-construct further:

reader.GetName(i) - this returns the name of the column

reader.GetValue(i).ToString() - this returns the value of the column as a string

getColumnName - a function the will return true if a column name can be gotten

?: - the conditional operator. If the expression before the ? is true, the expression to the left of the : is used, otherwise the one on the right

String.Format("<td>{0}</td", arg) - this will output "<td>arg</td>" (btw - your code is wrong, the ) should not be just after the first string)